The New Sudoku Players' Forum

[999_Springs]

i made this a while back by punching numbers into se at random and hitting f9 until i got something good. this may be a bit hard

Code: Select all

..9|..2|..7
...|.5.|9..
...|4..|...
---+---+---
.7.|...|4.5
...|26.|...
9.1|...|..2
---+---+---
6..|..9|.3.
5..|8..|.2.
8..|..1|..4

in other news today i've officially hit middle age
*moan* *grumble* *whinge* oh these kids of today
back in my day we didn't even have glow in the dark loo roll or motorised ice cream cones

oh and one other thing. i'd love to try out the puzzles that have been posted in this whole subforum, but if you keep posting them at like 2 AM then i'll never get a chance. i'm probably awake at that time but far too tired to do anything mentally stimulating, and by the time i get up in mid afternoon, all the solution paths have been taken

[JC Van Hay]

The key to this puzzle is obviously the cell r4c3.

[enxio27]

I have left forever. It's been a good 3.5 years or so, but I've moved on from sudoku.

Really sorry to see you go! I do hope you'll come back and visit every now and then.

[999_Springs]

I have left forever. It's been a good 3.5 years or so, but I've moved on from sudoku.

Really sorry to see you go! I do hope you'll come back and visit every now and then.

aww... i hadn't updated my sig since i left, so it's a bit misleading. i'd forgotten about that message

joined forum january 2007
3.5 years later ---> mid 2010, leaves for 3 years. (this is when i wrote that)
attempts comeback mid 2013, finds nobody at all is responding to his comeback posts. i'll probably be re-gone soon

[enxio27]

attempts comeback mid 2013, finds nobody at all is responding to his comeback posts. i'll probably be re-gone soon

I didn't realize you had left. I'm in and out myself, but I try to poke my head in here at least several times a week. It's sad to see the sudoku community dwindle to almost nothing. This forum seems to focus on finding hard sudokus and puzzles with specific patterns, and my other favorite forum (Richard Broughton's SudokuSolver forum) seems to focus mainly on killers. No one else seems interested in my favorites, which are gattai (samurai, sumo, etc.) and non-math, extra-constraint 9x9 (jigsaw, diagonal, windoku, etc.). At least I have enough puzzles in my collection to keep me busy for a while.

[StrmCkr]

Ive also been on/off again with sudoku spending my time on other stuff and family,
i've come back recently as well to reinvestigation where my solvers limit for coding was, and surpass where i was stuck coding took a lot of reading but finally i was able to see what i needed and advanced it.

by the way can someone tell me what's been happening in the sudoku world in the last five-halves years because i haven't been following

mostly rehashing conceptual ideas that have been floating around for a while: Muti-fish, different ways of implementing them from both programs and hand solvers point of view.

a few people have coded and are using:
S-wings, L-wings, M-wings, W wings, including your idea of inversion of weak/strong links...

purple cow name has been dropped pretty much for good, boo the name was funny to use.

hardest puzzles have gotten harder but not by much im sure we are in the upper limits for difficultly on a 9x9 grid.

minimal clues Of 17 was finally proven. there is no 16 clue puzzle.
There is no 16-clue sudoku: proof

several prominent websites for Sudoku lore/history and general information died or where overridden by spam bots.
sudokupeida,
some of the users here back it up on : http://sudopedia.enjoysudoku.com/Solving_Technique.html

sudoku.org.uk
is toast, nothing left of the forums... a few users have copies of it, but no one over there can be bothered to rebuild the content.

ive posted a few newish ideas but no one really payed attention to them...

[999_Springs]

thanks for the responses. it's disheartening to know that sudoku in general (and the purple cow name) has basically gone to scrap with no real chance of recovery

i do remember this place with much fondness, when i remember signing up as a gullible 13 year old who didn't know how to internet and this place served me well as a sort of introduction to internet as well as sudoku. i know forums naturally dwindle after a while but this place is just so dead. there are the patterns gamers (who may well all be robots), the nerdy people who make technical posts mainly about puzzle generation, and the 3-o'-clock-in-the-morning casual solvers. i didn't really know too much about other sudoku forums, but it looks like they're all dead too

i returned to this place hoping for some new innovation or inspiration to start sudoku-ing again, closest i can find is the exocet stuff and multi fish stuff that's been going on, but it seems completely intractable and technical to me. maybe i'll make a post asking for a gentle introduction to these things with the emphasis on manual solving, but i don't know if learning this is worth my time anymore

i have no idea why i'm still soliloquizing, i'm not doing this to get undue attention or anything. in a half baked attempt to stop derailing my own thread i'm going to point out the sue de coq in row 6 and block 6 that gives a single. also i literally just realised right now that a sue de coq is 2 applications of als xz i feel so dumb

edit: i'm surprised that the whole strong/weak link inversion turned out to have some application, link me to it if you can

also if you could start a cult following with my new names for aic's with 4 strong links that would be amazing

[StrmCkr]

http://dailysudoku.com/sudoku/forums/viewtopic.php?p=18998&sid=ade8d16da597c7b65ded3e5979af2b55#18998
which is actually older then your post on inversion but no where near as extensive

to paraphrase all the wings and their expressions,
notes: ive excluded wings that are not simplified als-xz or als-xy rules {ie wxyz- wing}, or fall under nxn fish {x-wing}.

Code: Select all

XY - Wing: (A=B) - (B=C) - (C=A)

XYX - wing: (A=B) - (B=AC) - (C=A)

gM - Wing: (A=B)   -  B  =   (B-A)   =   A

W - Wing: (A=B)   -  B  =  B  -   (B=A)

S - Wing: A  =  A  -   (A=B)   -  B  =   B   {1st A and last B in the same house}

L - Wing:  A  =  A  -  A  = (A  -  B) =   B   {1st A and last B in the same house}
(reverse): B  = (B  -  A) =  A  -  A  =   A   {1st B and last A in the same house}

H - WING: (A=B) - B = (B-C) = C
H - WING: (A=B) - (B=B) - C = C

basically from what i read:
if you change all weak links for strong links and replace all strong links with weak links, then add a strong link to start and end you now either have a new pattern or a morphed into an existing one.

so far the only one ive seen used is:

Code: Select all

 W-Wing: (a=b) - (b) = (b) - (b=a)
iW-Wing:  (a) = (a-b) = (b) - (b) = (b-a) = (a)

with an example: IW- wing

(5) r8c8 = (5-8) r7c8 = r2c8 - r1c7 = (8-5) r1c3 = r3c2 => -5 r8c2

Code: Select all

*--------------------------------------------------------------*
| 1     9    e58     | 2     6     7      |d58    4     3      |
| 278   27    4      | 9     3     5      | 1    c278   6      |
| 36   f257   36     | 1     8     4      | 257   27    9      |
|--------------------+--------------------+--------------------|
| 357   8     357    | 45    9     6      | 247   1     247    |
| 4     1     2      | 3     7     8      | 9     6     5      |
| 57    6     9      | 45    1     2      | 478   3     478    |
|--------------------+--------------------+--------------------|
| 578   4     578    | 6     2     9      | 3    b578   1      |
| 9     27-5  1      | 8     4     3      | 6    a257   27     |
| 268   3     68     | 7     5     1      | 248   9     248    |
*--------------------------------------------------------------*

[999_Springs]

if you change all weak links for strong links and replace all strong links with weak links, then add a strong link to start and end you now either have a new pattern or a morphed into an existing one.

that's a little bit different to my definition of inversion, where the strong link at the start and end that you add are now joined together and the candidate at the intersection is not an elimination but is true. (the extra strong links come from the fact that the elimination is weakly linked to the rest of the chain. that's what i'm inverting.)

if you did that to a w-wing as i pointed out you get a direct version of a purple cow

so if you invert a 7-link (discontinuous) wing and split the strong links you're always going to get one of the 9-link aic's that i documented. to be honest i don't really see the beauty of calling that thing an inverted w-wing, i mean if you find that pattern in a puzzle it's not exactly going to make you think, oh look, that's kind of like a w-wing, but different. it's a nice relationship, but when you're solving things it stands out as a pattern on its own. besides the name bananana that i gave that specific pattern is so much more catchy than inverted w-wing

so i don't see inversion being useful any time soon.

thanks for the link though

[Pat]

---there are the patterns gamers
(who may well all be robots),---

you caught me!
yes, i'm a robot

however,
the other players are probably human

[Pat]

i'd love to try out the puzzles that have been posted,
but if you keep posting them at like 2 AM
then i'll never get a chance

i'm usually on Lunar Standard Time

just posted this one in the Patterns Game
— does this suit you?

.17...2..58.9.....6.9.....1.9.6....7.....76......3..5.2...6.3.......9.8...14....2
[ play ]

{ edit: puzzle discussed at t=31342 }